Float-switch assembly



Oct. 28, 1952 D. H. M DONALD 2,516,003

FLOAT-SWITCH ASSEMBLY Filed May a, 1951 2 SHEETS-SHEET 1 Oct. 28, 1952D. H. M DONALD FLOAT-SWITCH ASSEMBLY 2 SHEETS-SHEET 2 Filed May 8, 1951w, "mm/A i atented (jet. 28 1952 FLOAT-SWITCH ASSEMBLY Dennison H.MacDonald, East Haven, Conn., assignor to Revere Corporation of America,Wallingford, Conn., a corporation of Connecticut Application May 8,1951, Serial No. 225,113

Claims.

This invention relates generally to float switches, and moreparticularly to float switch assemblies of the type used in tanks tocontrol the filling thereof.

It is an object of the present invention to provide a float switchassembly of this type which is of rugged and condensed construction andunimpaired by even strong liquid currents thereagainst, and which isnevertheless highly reliable in operation and sensitive in action,thereby to adapt the float switch assembly especially, though by nomeans exclusively, for installation in a liquid tank to exercise a safeand reliable control over the charging of the latter with liquid evenwhen it is forced therein under considerable pressure or at a high flowrate, or both.

It is another object of present invention to provide a float switchassembly of this type which will remain unimpaired even when subjectedto shock or vibration, thereby to render the float switch assemblyparticularly suited for installation in fuel tanks for air, sea or landcarriers, which are frequently subjected to these conditions.

It is a further object of present invention to provide a float switchassembly which lends itself not only to efficient mass production atrelatively low cost, but to ready installation in a tank as well.

Other objects and advantages will appear to those skilled in the artfrom the following, considered in conjunction with the accompanyingdrawings.

In the accompanying drawings, in which certain modes of carrying out thepresent invention are shown for illustrative purposes:

Fig. 1 is a part-sectional and part-elevational view of an installedfloat switch assembly embodying the present invention; Y

Fig. 2 is a section taken on the line 2-2 of Fig. 1;

Fig. 3 is a fragmentary section taken substantially on the line 33 ofFig. 2, with certain parts shown in elevation;

Fig. 4 is a fragmentary section taken substantially on the line 44 ofFig. 1.

Fig. 5 is a fragmentary section taken on the line 55 of Fig. l and Fig.6 is a fragmentary section similar to Fig. 3, and showing a modificationof the float switch assembly.

Referring to the drawings, and more particularly to Figs. 1 and 4thereof, the reference numeral In designates a float switch assemblywhich is shown installed in a liquid tank T. The

2 float-switch assembly [0 comprises a casing l4, a switch control unitI6 and a switch H.

The casing I4 is, in the present instance, in the form of a cylindricalshell which is closed at its bottom. Suitably mounted in the casing I4,as by spot-welding, for instance, is a bracket I8 which may be generallyrectangular in outline, and of a width to permit the unimpeded flow of aliquid L through the casing I4 (Figs. 2 and 4). A cover 20, which closesthe open bottom of the casing 14, may conveniently be held in positionby a screw 22 which is threadedly received by the bracket l8. Providedon top of the casing M is a cap 24 which is sealed from the interior ofthe casing M by an interposed partition 23. A peripheral margin of thepartition 26 is conveniently interposed between and welded or otherwisesecured to out-turned flanges 28 and 30 of the cap 24 and a sleeve 32,respectively. The sleeve 32 is, in turn, pressfitted on or otherwisesecured to a top length of the casing l4, so that the latter forms withthe cap 24 and the interposed partition 26 an integral unit. The sleeve32 on the casing I4 is provided with an out-turned flange 34 which issuitably secured, as by rivets 36, to the top wall 38 of the tank T, themajor part of the casing 14 extending into the interior of the tank Tthrough an aperture 39 in the top wall 38 thereof. The casing i4 is,within the confines of the tank T, provided with one or more inlets 40and one or more outlets 42. As best shown in Figs. 1 and 4, the inlets40 are provided near the bottom end of the casing l4, While the outlets42 are provided in the casing M in close proximity to the top wall 38 ofthe tank T.

The switch-control unit It is pivotally mounted on a support 50 whichmay be mounted on the bracket 26 by bolts 52 or the like. The support 50is in this instance, U-shaped as shown in Fig. 5, and threadedlyreceives in its opposite legs 54 and 56 screw-type studs 58 and 66,respectively, the adjacent ends of which are conically recessed to'serveas needle bearings for the conical ends 62 and 64, respectively, of apivot 66 on which an arm 68 of the switch-control unit 16 is firmlymounted. The studs 58 and may individually be turned for adjustment,while nuts 16 and I2 serve to lock the studs 58 and 66, respectively, incorrectly adjusted position to the support 50. One end of the arm 68 ofthe switch-control unit 16 carries a permanent magnet M, while asubstantial length of the arm 68 on the opposite side of the pivot 66 isenlarged to form a float-portion 3 16 which in this instance is a solidand integral part of the arm 68.

The pivot-axis of the switch-control unit 16, comprising the arm 68 withthe float-portion It thereof and the permanent magnet M, passes through,or substantially through, the center of gravity of said unit It so thatthe latter will in any angular disposition thereof be in neutralequilibrium.

Suitably mounted in an aperture 80 of the partition 25 in the casing Mis the open end of a tubular member 82 which is closed at its bottom 84,and extends into and is sealed from the interior of the casing it.Mounted in the tubular member 82 is the switch I? which, in the presentinstance, is provided in a sealed tube 86 of nonmagnetic and preferablyelectrical insulation material, such as glass, for instance (Fig. 4;.)Suitably carried in the opposite ends of the tube 36 are contact blades88 and 90 of which at least the latter is made of non-permanent magneticmaterial so as to be in magnetic relation with the permanent magnet M ofthe switch-contro1 unit I6 when the latter assumes the operativeposition shown in Fig. 1. The contact blade 90 is normally resilientlyurged into a position in which it is spaced from its companion blade 38,and is drawn into conductive engagement with the latter when in magneticrelation with the permanent magnet it of the switch-control unit itinthe operative position of the latter. The far ends of the contactblades 88 and 99 which project from the adjacent ends of the tube aresuitably connected to leads 32 and 94, respectively, which are alsoconnected with a relay 96 underneath the cap 2 The relay 9t mayin anysuitable manner control the circuit ofan electromagnetic filler-valvefor the tank T. Since the filler-valve and its circuit do not form partof the present invention, their disclosure is unnecessary.

Also suitably mounted on the support 50, in this instance on the leg 54thereof, is a permanent magnet lfill which is arranged in magneticallyree pellent relation with the permanent magnet Hi of the switch-controlunit It. so that the latter is normally urged by magnetic forces into.the.

inoperative position shown in Fig. 3 in which the float portion l6 ofthe arm 68 bears against the leg 55 of the support 56,.

As long as the level of the liquid Lin the tank T is below that shown inFig. 3, the switch-control unit it is magnetically urged into the in-.

operative position and closes the switch [8 to cause closure of thepreviously-mentioned fillervalve. Of course, as liquid is being drawnfrom the tank T and the level of the liquid therein drops, the repellentforces acting between the magnets M and Hit will cause theswitch-control unit It to return to its inoperative position.

The outlets 32 in the casing I4 serve as vents to assure at all timesequal air pressure above the liquid levels in the tank T and easing Mand, hence, the same liquid levels therein. While the switch-controlunit It may be located anywhere between the outlets 32 and inlets 10 inthe cas- 4 ing M as long as the switch I8 is properly coordinatedtherewith, the pivot axis of the switchcontrol unit is, in the presentinstance, on a level with the outlets t2 (Fig. 1) so that the tank willhave a maximum liquid capacity.

Reference is now had to Fig. 6 in which a modified switch-control unitit is shown. Thus, the arm 68 of the instant control unit is, incontrast to the solid float-portion 75 of the earlier-describedswitch-control unit it, provided with a hollow iloat 16' which may bemade of two complemental, edge-to-edge joined halves of which one may beintegral with or carried by the arm 68'. The pivot axis of the instantcontrol unit, comprising the arm 68' with the float 15' and thepermanent magnet M, passes also substantially through the center ofgravity of this unit so that the latter is in any angular positionthereof, in substantially neutral equilibrium.

The instant float-switch assembly which is rugged and condensed inconstruction and generally suitable for installation in liquid tanks ofall types, is highly reliable in operation and sensitive in its responseto a rising liquid level, as well as unimpaired by even strongliquid-currents thereagainst. Accordingly, the instant float-switchassembly is particularly well adapted for installation in fuel-tanks toexercise a safe and reliable control over the filling of the same evenwhen fuel is forced therein under consider able pressure or at a highflow rate, or both.

By virtue of the mounting of the switch-control unit so that the same isin any angular position in substantially neutral equilibrium, theinstant float-switch assembly will remain unimpaired even when subjectedto shock or vibration, and is, therefore, particularly suited forinstallation in fuel tanks for air, sea or land carriers which arefrequently subjected to these conditions.

Ihe invention may be carried out in other specific ways than thoseherein set forth without departing from the spirit and essentialcharacteristics of the invention, and the present embodiments are,therefore, to be considered in all respects as illustrative and notrestrictive, and all changes coming within the meaning and equivalencyrange of the appended claims are intended to be embraced therein.

I claim:

1. In a float-switch assembly, the combination of an arm pivotedintermediate its ends and hav-. ing at one side of its pivot axis afloat portion; a permanent magnet carried by said arm at the other sideof its pivot axis and forming with said arm a switch-control unit, the.pivot axis of said arm passing substantially through the center ofgravity of said unit so that the latter is in any angular position insubstantially neutral equilib-, rium; an electric switch havingcompanion contact members of which at least one member is ofnon-permanent magnetic material and in magnetic relation with saidpermanent magnet throughout a certain rotary range of said unit; andmeans normally yieldingly urging said unit into a home position spacedat an acute angle from the nearest limit of said certain range thereof.

2. The combination in a float-switch assembly as set forth in claim 1,in which said floatportion is an integral solid part of said arm adaptedfor partial immersion in and according displacement of, liquid so thatsaid arm part will rise with a rising liquid level.

3. The combination in a float-switch assembly as set forth in claim 1,in which said means com- REFERENCES CITED The following references areof record in the file of this patent:

5 UNITED STATES PATENTS Number Name Date 2,062,674 Pirwitz Dec. 1, 1936FOREIGN PATENTS 10 Number Country Date 476,114 Great Britain Dec. 2,1937

